Process of extracting metals from ores.



H. S. MAOKAY. PROCESS. FOR EXTRAGTING METALS PROM ORES. APPLICATIONFILED APR.16, 1913.

1,094,371 Patented Apr. 21, 1914.

MM 5] W00 Wcoz %1 (meme UNITED STATES PATENT OFFICE.

HENRY S. MACKAY, OF NORWICH, CONNECTICUT, ASSIGNOR T0 MACKAY PROCESSCOMPANY, OF NORWICH, CONNECTICUT, A CORPORATION OF DELAWARE.

Specification of Letters Patent.

Patented Apr. 21, 1914.

Application filed April 16, 1913. Serial N 0. 761,565.

To all whom it may concern Be it known that I, HENRY S. MAoKAY.

a citizen of the United States, and a resident of Norwich, Connecticut,have invented a new and useful Improvement in Processes for ExtractingMetals from Ores, of which the following is a specification.

My-invention relates to processes for extracting metals from ores and,particularly, for extracting metals from ores carrying a small ercentageof the desired metal.

It a so relates to the method of producing a solvent for extractingmetals from ores from the elements contained in the ores with theaddition of water.

The object of the invention is to provide a method of extracting metalsfrom ores wherein a solvent is made and maintained from the elements ofthe ore in the operation of the process.

A further object is to provide a process wherein the solvent willextract the desired metal from the ore and one which will be regeneratedimmediately upon removal of the desired metal from the solution; andwherein the metal deposited will be pure metal of commerce and requireno refinement outside of the process.

"There are for commercial reasons only two solvents that can be used;one is sulfuric acid and the other is hydrochloric acid. In order tosuccessfully extract and refine metal directly from ores it is necessarythat the solvent be produced from the'elements of the ore and in theoperation of the process. Not only is this necessary but also a solventmust be produced which will extract the metals, and one which will beregenerated up on the depositing of the metals from the solution. Thedesired metal deposited from the solution must be the pure metal ofcommerce. The process must be so conducted that the solution used as anelectrolyte will remainaspure as possible and contain no injurious.elements, and that the solvent formed will be of such a character a thatit will not-react wh-ile the desired metal To form a solvent or torefine the desired metal outside of the process adds so greatly to theexpense as to make a lixiviation process commercially impracticable. Asolvent to be most efficient must be a weak solution of an acid in orderthat it may be formed and maintained out of the elements of the ore. Aweak solution of the acid takes up less impurities than a strongsolution and it is ust as good a solvent if the ore is properlyprepared. There is a less loss of acid in' the mechanical operationofthe process, such as in replacing the solution carrying acid from theore, after extraction of the desired metal from the ore. By using a weaksolution of acid it can be maintained in the process in the lixiviationof ores carrying a very low percentage of sulfur.

The process is especially advantageous in the extraction of copper fromores; In the process sulfate of copper is formed. It may be formed byroasting the ore. If desired, and if the ore does not contain asuflicient amount of sulfur, sulfur may be added and then roasted. Thesulfur may be in any form, such as in sulfid ores or compounds, or puresulfur, the object being to roast the ore in the presence of sulfur,whether the sulfur be present in the ore or added thereto. WVhe n theores are roasted, sulfates and oxide of the metals contained therein areproduced, and also insoluble compounds of the undesired elements of theore, such as, ferric oxid, calcium sulfate, are formed. Part of thedesired metal may be extracted by the addition of Water, forming therebya solution ofthe sulfates of the desired metal of the ore. This solutionthen is conveyed to an electrolytic vat where a part of the desiredmetal will be deposited and an active solvent will be formed in thepresence of the sulfate of the desired metal.

Sulfuric acid may be formed in the solution or hydrochloric acid may beformed and used as the solvent. If is it desired to form sulfuric acidin the solution during the electrolysis, sulfate of the copper of theore will be decomposed, whereupon the'copper of the ore will bedeposited on the cathode plates and sulfuric acid will be formed in thesolution On the other hand, if it is desired to form hydrochloric acid,sodium chlorid is injected into the process'at any desired point, and bysubstitution, sodium sulfate and hydrochloric acid or chlorid of themetals are formed. When the solution carrying the chlorid of the copperis electrolized, the copper chlorid is decomposed as before and copperis deposited on the cathodes and hydrochloric acid is fomed in thesolution. Whether sulfuric acid or hydrochloric acid is formed in thesolution contained in the electrolytic vats, the solution iscontinuously applied to the ore and the ore is thoroughly leachedtherewith, removing the copper sulfate and the copper oxid or the copperchlorid which still remained after leaching with water. This solution iscontinuously conducted to an electrolytic vat Where the copper is decauses the formation of sulfates and oxids of the metals. This requiresvery little asulfur as the sulfur compounds immediately break up to formthe sulfates, while oxids of some of the metals are formed. All that isrequired is enough to form sulfates of part ofthe copper sufficient tomaintain the solvent formed by the electrolysis of the solution. Sulfurin any form is used and in any quantity but preferably enough to secureabout one part of sulfur to two of copper or even as low as one part ofsulfur to four of copper. This proportion may be varied according to thecharacter of the ore treated. Itdepends on the base elements in the oreto be neutralized. If it has considerable calcium more sulfur is used.If the orecarries a large amount of sulfur the excess of sulfur isdriven off until the iron is oxidized to an insoluble compound and thecopper is converted, to a soluble compound, such as CuSO, and CuO. I

In carrying out the process the ore is roasted at a low temperature inthe presence of sulfur, the sulfur being added if not present. The roastis then directed into a receptacle for cooling, if desired, and is thenconveyed or directed into a leaching vat where it is treated with water.This extracts the soluble sulfates of the copper which are taken up bythe solu tion. The solution is conveyed to an electrolytic tank where a(part of the copper sulfate isdecompose the copper is deposited andsulfuric acid Will be formed in the solution. The solution containingsulfuric acid and copper sulfate is used for leaching out the balance ofthe copper in the roasted ores existing in the form of copper oxid orsub-sulfate. This operation is continued until the solution is built upto a standard and contains copper sulfate, sulfuric acid and aluminumsulfate, if aluminum is in the ore. It is found that the best solutionfor extracting copper from ores carrying a low percentage of copper andsulfur should carry about 2% sulfuric acid and 2% copper in the form ofcopper sulfate. These percentages are varied in accordance with theamount of sulfur carried by the ore so as to form a solvent that can bemaintained from the elements of the ore in the process. When thestandard solution is formed, in the further continuance of the process,the ore is so roasted that the sulfur content is varied to maintain thisstandard solution, and without taking up the base or undesired elementsof the ore which fouls the solution when used as an electroyte. Thespecial advantage to be obtained by this process is to produce andmaintain a good solvent and a good electrolyte to enable theprecipitation of the copper from the electroyte as pure electrolyticcopper and maintain a substantially uniform electrolytic condition ofthe electrolyte. If it is desired to have a comparatively largepercentage of acid in the solution, it may be producedeither by'roastingthe ore so that a large per centage of sulfate is formed, or byincreasing the amount of sulfur in the mixture. This may be done byvarying the degree of temperature in the furnace. A low temperature notto exceed 600 degrees centigrade and the proper amount of oxygen, willform sulfates of copper and oxids'of iron. If too much sulfate isformed, by increasing the temperature above 600 degrees Centigrade, someof the sulfates are decomposed and more oxids of copper are formed whichin turnwill. consume acid in the solution. If there is an excess ofsulfuric acid the temperature may be raised so as to form oxids of themetals of the ore until the strength of the sulfuric acid is reduced. Inthis way the solvent may be maintainedin a most efiicient condition. Theacid formed in the solution will thus be balanced with the -Work it isrequired to dov aluminum. The aluminum sulfate immediately upon additionof the Water forms an 'arno Al2(SO4)3 scuo.=scuso AI2(OH).

A greater amount of copper is thus removed from the ore in the form ofcopper sulfate, upon the addition of water, than if no aluminum sulfatewas in the ore 'orin the roasted mixture. Upon electrolysis acid willattack copper oxid, formingcopper sulfate. If the sulfuric acid shouldbe completely used up the aluminum sulfate will in, turn attack thecopper oxid as before. This may be continued until all the copper oxidis removed, whereupon the aluminum sulfate will be carried into the vatwith the copper sulfate and upon electrolysis sulfuric acid is formed bythe decomposition of the copper sulfate and the solvent will containsulfuric acid and aluminum sulfate.

If it is desired that chlorids be formed from the sulfates of the metalsand hydrochloric acid produced instead of sulfuric acid in the solution,it may be done by adding sodium chlorid at various stages in theprocess, such as before the roast, to the sulfate solution, or beforeelectrolysis. After electrolysis of the solution containing chlori'ds,hydrochloric acid will be formed and this solution added to the ore actsupon the copper oxid and forms eupric chlorid and on the aluminumhydroxid and forms aluminum chlorid:

' 21101 cuo=cue1 H2O. J

31101 AI (0H) a- -srr,o Alon.

ango 2 1c1 scuo=acuc12 2A1 on The solution of cupric chlorid thus formedis then directed to the'electrolytic vat and electrolyzed, formingh'ydrochlorid acid. This when applied to the ore takes up copper oXidand the aluminum hydroxid as before. This is repeated until all thecopper oxid is removed and then the hydrochloric acid forms aluminumchlorid with the aluminum hydroxid. i v o It is desirable that thesolution should at all times contain some copper sulfate when sulfuricacid is used as solvent or some cupric chlorid when hydrochloric acid isused as a solvent, since the presence of the copper salt in the solutionproduces a good conductive electrolyte and at the same time it is asource from which sulfuric acid or hydrochloric acid may be formed.

The invention may be used in connection with many processes and suchprocesses may be greatly varied bythose ski-lied in the art withoutdeparting from the spirit of the invention.

-*In'-{t-he' .drawing is shown an apparatus or systemywherein one of themany processes covered by the claims and which involve the use of myinvention,- may be conducted.

The ore tobe treated is delivered to the furnacel by a chute 2. Thefurnace may be of any suitable type but I have shown here a furnace of awell known type which is provided with a central rotatable shaft 7having rakers S for constantly turning the ore and shifting it. throughits various compartments 9 While it is undergoing aroast. The rakers 8rake the ore from the top of the furnace where the ore is delivered fromthe chute 2 to and through the compartments of the furnace insuccession. During the roast the ore is kept at a proper temperature anda suitable amount of air is admitted for the proper length of time toproduce the desired proportion of the sulfate to the oxids of themetals. This treatment may be varied according to the character of'theores as heretofore described.

The ore is finally delivered through the chute 10 into a receptacle 4.The bottom of the receptacle 4 is hopper shaped and is provided with agate 5 which delivers the ore to a belt conveyer 6. The conveyer carriessuitable amounts of the ore to a leaching vat 15. In starting theprocesswater is then drawn through the pipe 14 and directed into the leachingvat 15. When it passes through the roasted ore, it leaches out thesoluble sulfates forming a solution thereof. The vat 15 is provided witha filter bottom 16 which will allow the liquid to pass into thecompartment 17 which is thus formed between the filter 16 and the bottomof the vat. The liquid from the ore is directed through a valve and pipe18 into a container 19.

lVhile the solution is in the container 19, it may be heated by steamwhich is allowed to enter through the valve and pipe 20. lVhen suitablyheated, preferably to about 50 degrees centigrade, it is allowed to flowthrough the valve 21 into the electrolytic tank 22 where the currentfrom the source 25 causes the deco nposition'of a part of the coppersulfate and thefc-rmation of sulfuric acid in the solution. The desiredmetal is removed from the solution as metallic plate. At the same timethat the copper is separated from the solution, the sulfion with whichit is combined is liberated at the anodes and there decomposes water andforms sulfuric acid. The cupric sulfate left in the solution forms agood conductor in the electrolyte and also forms a source of.

. sulfuric acid that may be drawn .upon by running the current a littlelonger. The solution is then collected in the receptacle 23. The platesmay be removed and the copper deposited thereon may be melted into barsin any form desired for commercial uses.

The-acid solution is pumped through the pipe 26 by means of the pump 27to the container 11. The solution from the electrolytic vat 22 iscirculated continuously through the vats and containers 23, ll, 15, p

19 and the vat and the copper is precipitated 1n vat 22 while the acidis recovered and part of the copper sulfate of the solution is carriedback to the leaching tank 15 where the acid takes up the copper in theore. When all of the copper has been removed from the ore, the solutionmay be removed from the tailings by adding water equal to the Weight ofthe solution in the tailings which replaces the solution as the solutionfilters down through the ore, the Water being left behind in the ore.The tailings of the ore are removed through the gate 28.

If sodium chlorid is added to the solution, the sulfates contained inthe ore are chan ed to the chlorids in the leaching vat 15 an a solutioncontaining cupric chlorid and sodium sulfate is formed. This isconducted to the electrolytic vat 22. Upon electrolysis of the solution,the copper is deposited upon the copper plates and the chlorin acts uponthe water to form hydrochloric acid in the solution. The solution isthen conducted to the container 23. From the receptacle 23, it isconducted through the vat 11 to the leaching vat 15, where the solventwill attack the copper still remaining in the ore. If any copper sulfatestill remains, the sodium chlorid remaining in the solution will formcupric chlorid and sodium sulfate and the hydrochloric acid. will actupon copper oxid and form cupric chlorid. A solution of cupric chloridis thus formeda second time. This is taken from the ore and againdirected through the vat 19 to the electrolytic vat 22, wherehydrochloric acid is again formed. The process is continuously carriedout as before and the steps are exactly the same as When thesulfuricacid is used as a solvent.

If excess of sodium chlorid is added to thesulfate solution, a smallamount of sodium chlorid will remain in the solution after electrolysis.If just enough is added to take up the sulfates, hydrochloric acid alonewill be produced in the electrolytic vat. If a less amount of sodiumchlorid is added to the solution and so that there will still remainsome of the sulfates, hydrochloric acid and sulfuric acid Will be formedin the electrolysis if continued.

If the ore contains aluminum, copper sulfate and aluminum sulfate willbe formed in the roast. The roasted ore is then conveyed to the leachingvat 15 and water is directed through the pipe 14 on to the ore. Thecopper sulfate and the aluminum sulfate are leached out of the ore. Thealuminum sulfate upon the addition of the water is dissolved and attacksthe-cupric oxid and forms copper sulfate, so that an additional amountof copper sulfate is leached out of the ore. The solution is thenconveyed to the electrolytic tank 22, where the copper sulfate isdecomposed, the copper being deposited on the cathodes and sulfuric acidbeing formed in the solution. The solution is then collected in thereceptacle 23 and raised to the container 11, from which it is drawn anddirected upon the ore. The sulfuric acid Will attack any copper oxidremaining in the ore and form aluminum sulfate by action upon thealuminum hydroxid that may remain. When all of the sulfuric acid is usedup the solution. Will contain aluminum sulfate which may be directedupon the ore.

If sodium chlorid is added to the solution before the electrolysis, thecopper sulfate in the solution is changed to' cupric chlorid andhydrochloric acid is formed in the electrolytic vat. W hen the solutionfrom the vat is directed upon the ore, the hydrochloric acid attacks thecopper oxid to form cupric chlorid and attacks the aluminum hydroxidformed by the addition of water in the preceding leach, and formsaluminum chlorid. The aluminum chlorid acts with the activity ofhydrochloric acid and forms an additional amount of cupric chlorid byits action upon any copper oXid that may remain in the ore. A solutionof cupric chlorid is thus drawn from the leach and directed to theelectrolytic vat where hydrochloric acid is again formed. Thehydrochloric acid solution is again directed upon the ore and if all ofthe copper oxid is removed from the ore,

aluminum chlorid may be formed from any ammonium hydroxid remaining inthe ore which may be directed upon a new charge of ore.

What I claim as new and desire to secure by Letters Patent is asfollows:

1. The process of extracting metals from ore containing sulfur whichconsists in pro ducing from the elements of the ore a solvent for themetal, electrolyzing the solution to extract the metal and, during theprocess,

continuoi'lsly treating the ore so as to produce and maintain a highefficiency of the solvent and electrolyte.

2. The process of extracting metals from ores which consists inproducing from the elements of the ore in the presence of sulfur asolvent for the metal, electrolyzing the solution toextract the metaland, during the process, continuously treating the ore so as to produceand maintain a high efficiency of the solvent and electrolyte.

3. In a process for extracting metals from ore the steps which consistin roasting the ore in the presence of sulfur, leaching andelectrolyzing, and controlling the composition of the solvent by thecharacter of the roast.

4-. A process for extracting metals from 5. A process for extractingmetals from ore which consists in forming a solvent for ores from theelements of the ore, by roasting the ore, leaching and electrolyzing,and controlling the composition of the solvent and the electrolyte bythe character of the roast.

6. A process for extracting metals from ores, which consists in forminga solvent from the elements of the ore by roasting charges of the ore inthe presence of a small amount of sulfur, leaching the roasted ore andelectrolyzing the leach, the roast being modified according to thecharacter of the solvent desired. v

7. A process for extracting metals from ore, which consists in roastingcharges of the ore in the presence of sulfur so as to pro duce a desiredproportion of the sulfates to the oxids of the metals of the ore,leaching and electrolyzing and'varying the solvent according to themanner in which the charges of ore are roasted.

8. A process for extracting metals from ore, which consists in roastingthe ore in the presence of sulfurso as to produce and maintain a desiredproportion of the sulfate to the oxids of the metals of the ore, so thatthe resultant solvent will dissolve the desired metal of the ore leavingthe undesired salts and bases in the ore, leaching and electrolyzmg.

- 9. A process for extracting metals from ores, which consists inroasting the ore in the presence of sulfur,'forming an insolublecompound with the undesired elements of the ore and soluble compoundswith the desired metals of the ore, leaching and electrolyzing, thecharges being leached by the solution produced by electrolysis.

10. A process for extracting metals from ores, which consists inroasting the ore in the presence of sulfur and forming insolublesulfates and oxids of the undesired'elements of the ore and solublesulfates and oxids of the desired metal of the ore, leaching andelectrolyzing, the charges of the ore being leached by the solutionproduced by the electrolysis.

11. Aprocess of extracting metals from ore which consists in formingsulfates of the desired metal of the ore by roasting the ore inthepresence of sulfur, leaching the ore and electrolyzing until thesolvent hasreached a desired character and degree of strength, modifyingthe roast so as to produce oxids and sullicient sulfates to keep thesolvent at the desired strength and character, leaching andelectrolyzing the solutions drawn from the ore and directing thesolution produced by electrolysis each time upon the roasted charges ofthe ore.

12. A process for extracting metals from ores, which consists intreating the ore, leaching the ore with asolvent, electrolyzing thesolution to deposit the desired metal of the ore and to regenerate thesolvent in the solution from the elements contained in the solution,regulating the solvent and the elec trolyte by the said treatment of theore and continuously leaching and electrolyzing and regenerating thesolvent and depositing the metal. 1

13. A process for extracting copper from ore, which consists in roastingthe ore in the presence of a small amount of sulfur compared to theamount of copper, leaching the ore and electrolyzing.

14. A process for extracting copper from ore, which consists in roastingthe ore in the presence of sulfur, the said sulfur being less in amountthan the copper contained in the ore, leaching the ore andelectrolyzing.

15. A process of extracting metals from ore, which consists in leachingthe ore with a solution containing about 2% sulfuric acid 4 andelectrolyzing the solution.

16. A process of extracting copper from ores, which consists in roastingthe ore in the presence of about one part of sulfur to four parts ofcopper to about two parts of sulfur to four parts of copper, leachingcharges of the ore and electrolyzing the solution and again leaching theore and electrolyzing, and so on continuously.

17. A process for extracting metals from ores, which consists inroasting the charges of the ore in the presence of a small amount ofsulfur in such a way that the desired elements may be extracted with aweak solution of sulfuric acid and a weak solution of sulfuric acid maybe formed and maintained in a solution from elements in the ore byleaching the roasted ore and electrolyzmg.

.18. A process for extracting metals from ore, which consists inroasting charges of the ore in the presence of a small amount of sulfur,leaching with a solution and elec trolyzing to produce a weak solution.of sulfuric acid, the roasting being such that the solution of sulfuricacid may be maintained insubsequent leaching of the chambers of the oreand electrolysis of the solution.

19. A process of extracting copper from ores which consists in roastingthe ore in the presence of a small amount of sulfur forming coppersulfate, leaching) with a solution and electrolyzing to decompose a partof the copper sulfate, continuously leaching the roasted ore with thesolution produced by electrolysis, and keeping a part of the coppersulfate in the solution.

20. A process of extracting copper from ores containing sulfur-andaluminum, which consists in roasting the ore so as to form sulfates andoxids of the desired metals of the ore, leaching with water andelectrolyzing lyzing the solution produced by leaching, and continuouslyleaching with the solution produced by electrolysis.

21. A process for extracting metals from ore which consists in roastingthe ore in the presence of sulfur so as to form sulfates and oxids ofthe metals of the ore, leaching the ore and electolyzing the solution,the roast being such that the sulfates and oxids of the metals of theore will be in such proportions that when the solution is electrolyzed adesired amount of the active agent will be produced in the solutionwithout injurious impurities. Y

22. A process for extracting metals from ores, which consists inroasting charges of the ore in the presence of a small amount of sulfurand so as to produce soluble compounds of the desired metals of the oreand insoluble compounds of the undesired metals of the ore and so thatupon continuous leaching and electrolyzing a weak solution of sulfuricacid and a good electrolyte will be formed and maintained, leaching theroasted ore, electrolyzing, and so on continuously leaching andelectrolyzing until the desired metal is extracted.

23. The process of extracting copper from ore containing iron, whichconsists in roasting the ore in the presence of sulfur in such a way asto form sulfate and oxid of copper and insoluble oxid of iron, leachingand electrolyzing, the ore being continuously leached with the solutionproduced by the electrolysis.

24. In a process of extracting copper from ores containing aluminum, thesteps which consist in forming a solvent from the elements of the ore byroasting the ore so as to produce sulfates of aluminum and copper andadding water.

25. A process of extracting metals from ore containing aluminum, whichconsists in forming a solvent from the elements of the ore by roastingthe ore in the presence of sulfur so as to produce the sulfates of themetals, leaching With a solution of sodium chlorid and electrolyzing thesolution.

26. A process of extracting copper from ore having aluminum, whichconsists in roasting the ore in the presence of sulfur, forming coppersulfate and aluminum sulfate, leaching the roasted ore and electrolyzingto decompose part of the copper sulfate, continuously leaching theroasted ore with the solution produced by the electrolysis andcontinuously keeping copper sulfate and aluminum sulfate in thesolution.

27. A process for extracting metals from ore, which consists inproducing a solvent for the ore from the elements of the ore by roastingthe ore in the presence of sulfur so as to produce a desired proportionof the sulfates to the oxids of the ore, leaching with water, addingsodium chlorid to the leach, electrolyzing and forming hydro chloricacid.

28. A process for extracting metals from ore, which consists in roastingthe ore in the presence of a small amount of sulfur and forming sulfatesof the metals of the ore, adding sodium chlorid solution to change apart of the sulfates to the chlorids, electrolyzing the solution so asto form hydrochloric acid and sulfuric acid.

29. A process of electro-chemically producing refined copper from copperore, which consists in forming a solvent from the elements of the ore inthe presence of sulfur, maintaining the character of the solvent and theelctrolyte by treating the ore without introducing any chemicals from anoutside source, and electrolyzing the said electrolyte.

30. A process for extracting metals from ore, which consists in treatingcharges of the ore so as to form and govern an active solvent with whichthe ore is treated and regulating by the treatment of the ore the saltsand bases formed in the solution from which the metal is extracted andelectrolyzing the solution to precipitate the metal and regenerate thesolvent.

31. A process of extracting metals from .ore, which consists in roastingcrushed ore, leaching the ore, electrolyzing the solution with which theore is leached thereby obtaining refined metal, the character of thesolvent and the electrolyte being formed, maintained and controlledbythe roasting and leaching of the ore, and the solvent being regeneratedby the electrolysis.

/ In testimony whereof, I have signedmy name to this specification inthe presence of two subscribing witnesses.

HENRY S. MAGKAY.

Witnesses FRANK F. CRAMPTON, MILTON W. SAMETZ.

